1. Field of the Invention Field
The present invention relates to an engine, and more particularly to an engine having a crankshaft with a crankcase having a plurality of bearing portions for rotatably supporting the crankshaft, each of the bearing portions being dividable along a divisional plane arranged on the axis of the crankshaft. Cylinder barrels are connected to the crankcase with the cylinder barrels having cylinder bores with axes that are perpendicular to the divisional plane. The cylinder heads are connected to the cylinder barrels.
2. Description of Background Art
In a conventional engine disclosed in Japanese Patent Laid-Open No. 2002-213302, for example, a crankcase, cylinder barrels, and cylinder heads are formed as separate members. The cylinder barrels are fastened to the crankcase, and the cylinder heads are fastened to the cylinder barrels with gaskets interposed therebetween.
In the above conventional structure, the number of bolts for fastening the crankcase, the cylinder barrels, and the cylinder heads is large, and it is hard to say that the mountability and maintainability are excellent. Further, since the gaskets for high temperature and high pressure are interposed between the cylinder barrels and the cylinder heads, the fastening loads on the cylinder barrels and the cylinder heads must be set to a large value, so that the space and weight occupied by such fastening portions of the cylinder barrels and the cylinder heads become relatively large.